A fuel cell vehicle and an electric vehicle each have a high-power device for controlling an electric traction motor installed therein. The high-power device may for example be a power converter configured to convert power from a power source to driving power for the traction motor. Since the high-power device generates a large heat quantity, the vehicle is provided with a cooling apparatus for cooling a device having such a large heat quantity. Since a fuel cell also generates a large heat quantity, it is provided with a cooling apparatus. The cooling apparatus is configured to pump a refrigerant to the device (including the fuel cell) using a pump. For convenience, “an electric traction motor” may be called as “a traction motor” hereinafter.
On the other hand, the vehicle which runs on the traction motor exhibits superior quietness, so an operation sound of the pump may become a noise while running at a low speed. Thus, for example, a cooling apparatus described in JP 2013-38990 A sets a rotational speed of a pump so that a resonant frequency of a vehicle body and a vibration frequency of the pump do not match. A cooling apparatus described in JP 2011-160597 A lowers an output command value for a pump in a case where a vehicle speed is lower than a vehicle speed threshold value so that a vibration frequency of the pump does not match a resonant frequency of a vehicle body.